There is a film formation device in which a single-crystal film is epitaxially grown on a surface of a substrate such as a wafer using a CVD (Chemical Vapor Deposition) method. In such a film forming apparatus, a process chamber, a susceptor, on which a substrate is placed, a heater which heats the substrate placed on the susceptor, a rotating portion which rotates the susceptor, a liner which has a cylindrical shape and is provided with one opening end facing the substrate, and a gas supply portion which supplies a process gas to the other opening end of the liner are provided. Further, there is also a case where a heater is further provided on an outer surface of the liner.
By providing the liner, the process gas supplied from the gas supply portion can be efficiently guided to the surface of the substrate.
However, when the liner is heated by the heater, a reaction product such as a crystal is formed also on an inner wall of the liner in some cases. When the reaction product is formed on the inner wall of the liner, due to repetitive rise and fall of temperature accompanying the operation of the film forming apparatus, the reaction product falls off and a particle may be generated. When a particle is generated, the particle becomes a factor to deteriorate the quality of a film formed on the surface of the substrate. In this case, if a process for performing an etching treatment of the wall surface after a film formation treatment of the substrate is added, or the operation of the film forming apparatus is stopped and the liner is cleaned on a regular basis, the generation of a particle can be suppressed. However, when a process for performing an etching treatment of the wall surface is added or the operation of the film forming apparatus is stopped for performing cleaning, operation efficiency is decreased. Further, in the case where the heater is provided on the outer surface of the liner, a temperature of the liner becomes higher than a temperature of the substrate, and therefore, the reaction product may be more likely to be formed, or a service life of the liner may be reduced.
Further, when a gas is supplied to a space partitioned by the substrate and the liner to effect heating, heat convection occurs. The occurrence of convection also affects the flow of the gas supplied to the substrate, and the uniformity of film formation may be deteriorated, a time for changing the type of gas may be increased, a reaction product generated on the surface of the substrate or in the vicinity of the substrate may be adhered to the liner. In order to prevent the occurrence of these problems, the liner is formed of a material resistant to high temperatures and has a large and complicated shape. Therefore, the production cost of the liner is high.
In view of this, development of a technique capable of improving the quality of the film and productivity has been demanded.